@media (max-width: 900px) {
  header nav ul {
    flex-direction: column;
    align-items: center;
  }

  header nav ul li {
    margin: 0.5rem 0;
  }

  main {
    padding: 4rem 1rem 3rem;
  }

  .portfolio-hero__gallery {
    order: -1;
  }

  .gallery-controls {
    width: 100%;
    justify-content: space-between;
  }
}